Abstract
Introduction. Autoimmune encephalitis (AE) is a clinically challenging diagnosis with nonspecific neurological symptoms. Prompt diagnosis is important and often relies on neuroimaging. We present a case series of AE highlighting the importance of an early [18F]-fluoro-deoxy-glucose positron emission tomography (FDG-PET) scan. Methods. Retrospective review of seven consecutive cases of autoimmune encephalitis. Results. All patients had both magnetic resonance imaging (MRI) and FDG-PET scans. Initial clinical presentations included altered mental status and/or new onset seizures. Six cases had serum voltage-gated potassium channel (VGKC) antibody and one had serum N-methyl-D-aspartate (NMDA) antibody. MRI of brain showed mesial temporal lobe hyperintensity in five cases of VGKC. The other two patients with VGKC or NMDA AE had restiform body hyperintensity on MRI brain or a normal MRI, respectively. Mesial temporal lobe hypermetabolism was noted in three cases on FDG-PET, despite initial unremarkable MRI. Malignancy workup was negative in all patients. Conclusion. A high index of suspicion for AE should be maintained in patients presenting with cognitive symptoms, seizures, and limbic changes on neuroimaging. In cases with normal initial brain MRI, FDG-PET can be positive. Additionally, extralimbic hyperintensity on MRI may also be observed.
Highlights
Autoimmune encephalitis (AE) is a clinically challenging diagnosis with nonspecific neurological symptoms
We present seven patients with AE highlighting the importance of early neuroimaging with brain magnetic
Computed tomography (CT) of head was unremarkable for any acute process in all the presented cases. This case series of VGKC and NMDA autoimmune encephalitis illustrates the importance of neuroimaging with emphasis of early fluoro-deoxy-glucose positron emission tomography (FDG-PET) in cases of initial nondiagnostic magnetic resonance imaging (MRI)
Summary
Autoimmune encephalitis (AE) is a clinically challenging diagnosis with nonspecific neurological symptoms. MRI of brain showed mesial temporal lobe hyperintensity in five cases of VGKC. Mesial temporal lobe hypermetabolism was noted in three cases on FDG-PET, despite initial unremarkable MRI. In cases with normal initial brain MRI, FDG-PET can be positive. Autoimmune encephalitis (AE) is a clinically challenging diagnosis usually suspected in cases of altered mental status or seizures after excluding other more common diagnoses. (Anderson 2008) Common presenting signs are nonspecificmemory impairment, hallucinations, anxiety, irritability, depression, seizures, or sleep alterations [1, 2] These symptoms may develop over a course of weeks to months. Early neuroimaging, along with the initial neurological assessment, plays an important role [6, 7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
